1. Field of the Invention
The present invention relates to a clamp for use in clamping an ignition cable in position that is provided to connect an electrode of a distributor of an internal combustion engine mounted on an automotive vehicle or the like with an ignition plug of the internal combustion engine.
2. Prior Art
One of the wide range of applications of ignition cables is for automotive vehicles. In automotive vehicles, a number of ignition plugs are employed, and this involves complicated wiring of ignition cables. In addition, ignition cables are subject to vibrations and heat generated in a high temperature atmosphere. In these circumstances, with a view to obtaining stable functions of ignition cables clamps are used to put wiring of ignition cables in good order, as well as holding the same in position. In general, in a widely employed ignition cable clamping structure, clamps are provided on a rocker arm cover separately in such a manner as to stand erect therefrom, and each ignition cable is clamped to be held at an intermediate position along the length thereof by an associated clamp.
However, this commonly used ignition cable clamping structure is disadvantageous in that it involves a need for machining of the rocker arm cover so as to make it possible to provide clamps in such a manner as to stand erect therefrom, and requires metal fixtures for fixing clamps so provided on the rocker arm cover. With a view to solving the above problem, the official gazette of Japanese Utility Model Laid-Open No. 167479/86 discloses an ignition cable clamping device adapted to eliminate a need for provision of clamps on the rocker arm cover. In this clamping device, a notch is formed in the clamp portion integrally provided on a rubber ignition plug cap (hereinafter, simply referred to as plug cap) enclosing the end portion of an associated ignition cable in such a manner as to protrude therefrom, and another ignition cable passing by this plug cap is designed to be held by this notch.
In this clamping device comprising a notch formed in the clamp portion integrally provided on the plug cap, since the clamp portion in which a notch is formed is formed as an integral portion of the rubber plug cap, basically the clamp portion for holding an ignition cable also comprises an elastic member.
Due to this construction, the conventional clamping device disclosed in the above-mentioned official gazette has the following drawbacks. In case where the frequency of vibrations of the engine on the ignition plug side does not coincide with that of vibrations of the ignition cable resiliently held in the clamp portion, vibrating stress is generated at the clamp portion serving as a point of contact between these two vibrations having different frequencies, and this tends to cause damage and/or deterioration of the clamp portion. In addition, the rubber clamp portion is subject to heat deterioration due to the high temperature atmosphere in which it is placed. This heat deterioration adds to with the vibrating deterioration, and this synergistic effect sometimes serves to quickly deteriorate the clamping capability of the clamp portion. Furthermore, since the plug cap and clamp portion are integrally formed, there is no possibility of varying the wiring layout of ignition cables, and hence this construction lacks flexibility to allow changes in a wiring layout of ignition cables.